修复swift tuner bug

KulexiuForStudent/KulexiuForStudent/Module/Widget/Model/TuningFunction/Tuner.swift

@@ -136,7 +136,7 @@ private let frequencies: [Float] = [
      Object adopting the TunerDelegate protocol that should receive callbacks
      from this tuner.
      */
-    @objc public var delegate: TunerDelegate?
+    @objc public weak var delegate: TunerDelegate?
     
     /**
      Initializes a new Tuner.